EDIT

        TaxonNode node = taxonNodeService.find(nodeUuid);

        if(node == null){

            logger.warn("The specified taxon is not found in the given tree.");

        }else if (subtree != null && !node.isDescendant(subtree)){

            //TODO handle as exception? E.g. FilterException, AccessDeniedException?

            logger.warn("The specified taxon is not found for the given subtree.");

        }

        return loadTreeBranch(node, subtree, baseRank, includeUnpublished, propertyPaths);